In a large sauce pan, melt butter over medium heat. Whisk in flour to thicken, taking care not to burn, and then gradually whisk in milk until mixture is semi-thick and smooth. Continue whisking while adding beer. Next, gradually whisk in cheeses allowing each addition of cheese to melt before adding the next. Once cheese is melted, whisk in mustard, Worcestershire and cayenne. Add salt and pepper to taste to bring out flavors. Serve warm with thin Italian breadsticks and slices of French baguette for dipping. Stick breadsticks into the sliced bread to create "broomsticks".